1. Field of the Invention
The present invention relates to data processing and vehicle navigation. More particularly, this invention relates to methods and systems that allow one to better allocate and assign arrival/departure slot times for a plurality of aircraft into and out of a system resource, like an airport.
2. Description of the Related Art
The need for and advantages for tracking, prediction and asset allocation systems to better manage complex, multi-faceted processes have long been recognized. It has long been recognized by many industries that having a certain part or set of materials at a certain place at just the right time yields significant efficiencies. Thus, many complex methods for tracking and managing material flows based on the future position of particular assets as a function of time have been developed.
However, as applied to tracking, prediction and managing of aircraft within the aviation industry, such methods often have been fragmentary and too late in the process to effect the necessary change to provide real benefit. Additionally, these methods typically have not addressed the present and future movement of the aircraft, combined with other factors that can alter the aircraft""s trajectory into/out of a system resource (e.g., airport).
Aviation regulatory authorities (e.g., various Civil Aviation Authorities, CAA, throughout the world, including the Federal Aviation Administration, FAA, within the U.S.) are responsible for matters such as the separation of in-flight aircraft. In this task, the CAAs collect and disseminate considerable data concerning the location of aircraft within the airspace system. This data includes: radar data, verbal position reports, data link position reports (ADS), etc. Further, airlines and other aircraft operators have developed their own flight following systems as required by the world""s CAAs, which provide additional information concerning the position of the aircraft. Additionally, third parties have developed their own proprietary systems to track aircraft (e.g., Passur).
In the current art, various independent agencies, airlines or third parties use these data sources. There appears to have been few successful attempts by the various airlines/CAAs/airports/military operations/third parties to develop accurate methods and processes to manage and allocate capacity constrained resources (i.e., tactical slot allocation) that encompass all of the real-time factors (weather, ATC, individual pilot decisions, turbulence, capacity, demand, etc.) that can affect the trajectory of an aircraft. For example, in the current art of management of aircraft into an airport, it often happens that the arrival sequence is accomplished too early or too late in the arrival/departure process that actions taken have a negative effect on the efficient use of the aircraft/runway/airport assets.
An example of one of these elements is the ATC response to too many aircraft trying to land at an airport in a defined period of time. In the current art, the prediction of the aircraft arrival/departure slot time is not as accurate as possible since it is predicated only on the current aircraft position, speed, flight path and possibly winds. Yet, even with this limited information available, the arrival flow system rarely uses this information in real time to temporally manage the flow of aircraft into the airport. It is only as the aircraft nears the airport (within the last 100 to 150 miles) that the local ATC controller begins to manage the sequencing of the aircraft. And, even if the CAAs use this prediction information, it is only to limit the arrival flow based on distance sequencing of the flow (i.e., 20 miles nose to nose spacing) as opposed to the method of time based sequencing embodied in the present invention. Further, by waiting so late in the arrival process to sequence the aircraft, the controller has only one sequencing optionxe2x80x94delays.
This process is analogous to the xe2x80x9ctake a ticket and waitxe2x80x9d approach used in other industries. To assure equitable service to all customers, as the consumer approaches a crowded counter, the vendor sets up a ticket dispenser with numbered tickets. On the wall behind the counter is a device displaying xe2x80x9cNow Servingxe2x80x9d and the number. This xe2x80x9cfirst come, first servexe2x80x9d process assures that no one customer waits significantly longer than any other customer.
The effect of the ATC""s xe2x80x9ctake a ticket and waitxe2x80x9d approach, as applied in a distance based manner and once the aircraft is near the destination airport or near the takeoff runway, is to add 1, 5, 10, 15 or more minutes to an aircraft""s actual arrival time.
Only by incorporating all of the flights landing and departing at a particular airport, combined with the capacity of that airport and potential weather effects, all of which are encompassed in the present invention, can one more accurately predict, allocate and manage the arrival/departure slot times of all of the aircraft. In other words, the present invention views each aircraft as part of a system, and not individually as done within the current art.
For example, FAA""s Collaborative Decision Making (CDM) program (a system to disseminate data) took a major step forward by providing both air traffic controllers and airlines with the same real time data. However, airline dispatchers, pilots, and ATC controllers are still acting mostly independently in the use of this data and are optimizing complex situations locally. Further, the competing goals of all of the different segments of the National Airspace System (NAS) often conflict, leading to confusion and wasted capacity.
For another example, a pilot may request a specific runway to save fuel and reduce taxi time even though the flight is early. The controller tries to accommodate the request and creates additional work, while blocking another aircraft that is already late from using the close in runway. As often as not, these aircraft are from the same airline.
Yet another example is when an ATC controller tries to sequence two aircraft within his sector for an arrival fix 400 miles down line. To do this, one aircraft is sped up and another slowed down or turned off course. Unfortunately, the fact that the original speeds and trajectories of each aircraft assured that the sequence at the corner post was not a problem was unknown to the local ATC controller.
To begin to understand how the current methods and system might be improved upon, it is first necessary to have a basic understanding of the various processes surrounding the flight of an aircraft. FIG. 1 has been provided to indicate the various segments in a typical aircraft flight process. It begins with the filing of a flight plan by the airline/pilot with a CAA. Next, the pilot arrives at the airport, starts the engine, taxis, takes off, flies the flight plan (e.g., route of flight), lands and taxis to parking. At each stage during the movement of the aircraft on an IFR flight plan, the CAA""s Air Traffic Control (ATC) system must approve any change to the trajectory of the aircraft. Further, anytime an aircraft on an IFR flight plan is moving, an ATC controller is responsible for ensuring that an adequate separation from other IFR aircraft is maintained.
During the last part of a flight, typical initial arrival/departure sequencing is accomplished on a first come, first serve basis (e.g., the aircraft closest to the airport is first, next closest is second and so on) by the enroute ATC center near the arrival airport (within approximately 100 miles of the airport), refined by the arrival/departure ATC facility (within approximately 25 miles of the arrival/departure airport), and then approved for arrival by the local ATC tower (within approximately 5 to 10 miles of the arrival/departure airport).
For example, current CAA practices for managing arrivals at arrival/departure airports involve sequencing aircraft arrivals by linearizing an airport""s traffic arrival/departure aircraft flows according to very structured, three-dimensional, aircraft arrival/departure paths, 100 to 200 miles from the airport or by holding incoming aircraft at their departure airports. For a large hub airport (e.g., Chicago, Dallas, and Atlanta), these paths involve specific geographic points that are separated by approximately ninety degrees (see FIG. 2), 30 to 50 miles from the airport. Further, if the traffic into an airport is relatively continuous over a period of time, the linearization of the aircraft flow is effectively completed hundreds of miles from landing. This can significantly restrict all the aircraft""s arrival speeds and alter the expected arrival slot time, since all in the line of arriving aircraft are limited to the speed of the slowest aircraft in the line ahead.
The temporal variations in the arrival/departure slot times of aircraft into or out of an airport can be quite significant. FIG. 3 shows for the Dallas-Ft. Worth Airport the times of arrival at the airport""s runways for the aircraft arriving during the thirty minute time period from 22:01 to 22:30. It can be seen that the numbers of aircraft arriving during the consecutive, five-minute intervals during this period were 12, 13, 6, 8, 6 and 5, respectively.
Further, much of the current thinking concerning the airline/ATC delay problem is that it stems from the over scheduling by the airlines of too many aircraft into too few runways. While this may be true in part, it is also the case that the many apparently independent decisions that are made by an airline""s staff (i.e., pilots, customer service agents, etc.) and various ATC controllers may significantly contribute to airline/ATC delay problems. And while many of these decisions are predictable, in the current art, they have yet to be accounted for and/or coordinated in real time from a system perspective.
These delays are especially problematic since they are seen to be cumulative. FIG. 4 shows, for all airlines and a number of U.S. airports, the percentage of aircraft arriving on time during various one-hour periods throughout a typical day. This on time arrival performance is seen to deteriorate throughout the day.
The current art of aircraft arrival/departure sequencing (to assure proper aircraft separation) to an airport or other system resource, can be broken down into seven distinct tools used by air traffic controllers, as applied in a first come, first served basis, and include:
1. Structured Dogleg Arrival/Departure Routesxe2x80x94The structured routings into an arrival/departure are typically designed with doglegs. The design of the dogleg is two straight segments joined by an angle of less than 180 degrees. The purpose of the dogleg is to allow controllers to cut the corner as necessary to maintain the correct spacing between arrival/departure aircraft.
2. Vectoring and Speed Controlxe2x80x94If the actual spacing is more or less than the desired spacing, the controller can alter the speed of the aircraft to correct the spacing. Additionally, if the spacing is significantly smaller than desired, the controller can vector (turn) the aircraft off the route momentarily to increase the spacing. Given the last minute nature of these actions (within 100 mile of the airport), the outcome of such actions is limited.
3. The Approach Trombonexe2x80x94If too many aircraft arrive at a particular airport in a given period of time, the distance between the runway and base leg can be increased; see FIG. 5. This effectively lengthens the final approach and downwind legs, allowing the controller to xe2x80x9cstorexe2x80x9d or warehouse in-flight aircraft.
4. Miles in Trailxe2x80x94If the approach trombone can""t handle the over demand for the runway asset, the ATC system begins spreading out the arrival/departure slot times linearly. It does this by implementing xe2x80x9cmiles-in-trailxe2x80x9d restrictions. Effectively, as the aircraft approach the airport for arrival/departure, instead of 5 to 10 miles between aircraft on the linear arrival/departure path, the controllers begin spacing the aircraft at 20 or more miles in trail, one behind the other; see FIG. 6.
5. Ground Holdsxe2x80x94If the separation authorities anticipate that the approach trombone and the miles-in-trail methods will not hold the aircraft overload, aircraft are held at their departure point and metered into the system using assigned takeoff times.
6. Holdingxe2x80x94If events happen too quickly, the controllers are forced to use airborne holding. Although this can be done anywhere in the system, this is usual done at one of the arrival/departures to an airport. Aircraft enter the xe2x80x9cholding stackxe2x80x9d from the enroute airspace at the top; see FIG. 7. Each holding pattern is approximately 10 to 20 miles long and 3 to 5 miles wide. As aircraft exit the bottom of the stack towards the airport, aircraft orbiting above are moved down 1,000 feet to the next level.
7. Reroutexe2x80x94If a section of airspace, enroute center, or airport is projected to become overloaded, the aviation authority occasionally reroutes individual aircraft over a longer lateral route to delay the aircraft""s entry to the predicted congestion.
CAAs current air traffic handling procedures are seen to result in significant inefficiencies and delays. Thus, despite the above noted prior art, a need continues to exist for better methods and systems to allocate and manage the arrival/departure slot times of a plurality of aircraft into and out of a system resource, like an airport.
The present invention is generally directed towards mitigating the limitations and problems identified with prior methods used to allocate arrival/departure slot times of aircraft. Specifically, the present invention is designed to more accurately, efficiently and safely manage and allocate arrival/departure slot times for aircraft.
In accordance with the present invention, a preferred embodiment of this invention takes the form of a computer program for controlling a processor to allow an aviation system to temporally allocate aircraft slot times during a specified period for the flow of a plurality of aircraft toward a specified fix point, based upon specified data pertaining to the aircraft, the fix point and associated system resources, and aviation system specified criteria for allocating the slot times.
This computer program includes: (1) a means for collecting and storing the specified data and criteria, (2) a means for processing, at a specified instant for which it is desired to allocate the slot times, the specified data applicable at that instant to each of the aircraft and associated resources so as to predict an arrival fix time for each of the aircraft at the specified fix point, (3) a means for assigning to each of the plurality of aircraft a figure of merit whose value is a measure of how likely it is that the predicted arrival fix time will be achieved by the aircraft, wherein the figure of merit having a specified value, which, when exceeded, implies that the predicted arrival time is sufficiently reliable so as to warrant the aircraft to be considered for an allocation of one of the slot times, (4) a means for accepting and storing a request by the operator of each of the aircraft for one of the slot times, (5) a means for accepting and storing a request by an operator of the present invention to create slack time in the specified period, (6) a means, utilizing the slot and slack time requests and the predicted arrival fix times for any of the plurality of aircraft for which a slot time request was not made, for predicting the demand for the slot times, (7) a means, based upon specified data that is applicable to the specified period and fix point, for predicting the availability of the slot times within the specified period, (8) a means for allocating the slot times, with this means including: (i) a means for directing a communication device, which is accessible by the aircraft operators and an operator of the present invention, to communicate the relative situation of each of the aircraft approaching the fix point versus the available slot times and the requests of the other operators, (ii) a means for comparing the demand for, versus the availability of, slot times to determine whether a conflict exists for a slot time, (iii) a means for identifying and evaluating alternative ways to resolve conflicts for the slot times, (iv) a means which considers the alternative ways to resolve slot time conflicts and yields a recommendation for resolving the conflict, (v) a means for communicating the recommended conflict resolution to the affected operators, (vi) a means for collecting and storing the input of the operators pertaining to the allocation of the slot times, and (vii) a means, responsive to the requests and the operator input, for allocating the slot times, (9) a means that facilitates the trading of the allocated slot times among the aircraft operators, and (10) when the specified data is temporally varying, the computer program further includes: (i) a means for monitoring the ongoing temporal changes in the specified data so as to identify temporally-updated specified data, (ii) a means for updating the arrival fix times for each of the aircraft to which the temporally-updated specified data applies, (iii) a means for updating the predicted demand for and availability of slot times based upon the updated arrival fix times, and (iii) a means for updating the allocations based upon the updated predictions of the demand for and availability of slot times.
In another preferred embodiment, the present invention takes the form of a method that allows an aviation system to temporally allocate aircraft slot times during a specified period for the flow of a plurality of aircraft toward a specified fix point, based upon specified data pertaining to the aircraft, the fix point and associated system resources, and aviation system specified criteria for allocating the slot times.
This method includes the steps of (1) collecting and storing the specified data and criteria, (2) processing, at a specified instant for which it is desired to allocate the slot times, the specified data applicable at that instant to each of the aircraft and associated resources so as to predict an arrival fix time for each of the aircraft at the specified fix point, (3) assigning to each of the plurality of aircraft a figure of merit whose value is a measure of how likely it is that the predicted arrival fix time will be achieved by the aircraft, wherein the figure of merit having a specified value, which, when exceeded, implies that the predicted arrival time is sufficiently reliable so as to warrant the aircraft to be considered for an allocation of one of the slot times, (4) accepting and storing a request by the operator of each of the aircraft for one of the slot times, (5) accepting and storing a request by the airline system to create slack time in the specified period, (6) predicting, utilizing the slot and slack time requests and the predicted arrival fix times for any of the plurality of aircraft for which a slot time request was not made, the demand for the slot times, (7) predicting, based upon specified data that is applicable to the specified period and fix point, the availability of the slot times within the specified period, and (8) allocating, based upon the operator requests, predicted demand for and availability of the slot times and the slot time allocation criteria, the slot times.
Thus, there has been summarized above, rather broadly, the present invention in order that the detailed description that follows may be better understood and appreciated. There are, of course, additional features of the invention that will be described hereinafter and which will form the subject matter of any eventual claims to this invention.
To better understand the invention disclosed herein, it is instructive to consider the objects and advantages of the present invention.
It is an object of the present invention to temporally manage the flow of aircraft through the allocation of arrival/departure slot times, rather than through the application of distance-based sequencing or by temporally denying access to the entire system.
It is another object of the present invention to build a network where users can claim, alter, exchange, etc. arrival/departure slots in real time.
It is yet another object of the present invention to provide a method and system to better allocate aircraft arrival/departure slot times for x hours into the future (i.e., 1 32 to 24 hours), with respect to a plurality of aircraft at a specified system resource, like an arrival/departure fix, runway, airport, airway, airspace, ATC sector or set of resources, thereby overcoming the limitations of the prior art described above.
It is still another object of the present invention to present a method and system for the real time tracking and prediction of aircraft that takes into consideration a wider array of real time parameters and factors that heretofore were not considered. For example, such parameters and factors may include: aircraft related factors (e.g., speed, fuel, altitude, route, turbulence, winds, weather), ground services (gates, maintenance requirements, crew availability, etc.) and common asset availability (e.g., runways, airspace, Air Traffic Control (ATC) services).
It is a further object of the present invention to provide a method and system that will enable the airspace users to better manage their aircraft.
It is a still further object of the present invention to temporally allocate the arrival/departure slot times of aircraft into or out of a specific system resource in real time. Further, if the outcome of events alters demand or capacity for that system resource, it is then the object of the present invention to account for these problems in the arrival/departure allocations within the present invention such that arrival/departure slot times are reallocated so as to more efficiently use the constrained resource.
These and other objects and advantages of the present invention will become readily apparent, as the invention is better understood by reference to the accompanying drawings and the detailed description that follows.